1. Field of Invention
Mosquitoes, flies, ticks, fleas and chiggers are of significant economical and medical concern because humans and important species of wild and domestic animals are inconvenienced, annoyed, sickened and on occasion killed as a result of their bites. This invention relates to a means and method of attracting, trapping and disposing of them.
2. Discussion of Related Art
Mosquitoes, flies, ticks, fleas and chiggers carry a wide range of blood borne diseases which readily infect humans and animals when bitten. These diseases include among other things, lyme disease, ehrlichiosis, tularemia, vectored borreliosis (Masters disease), encephalitis, West Nile virus, Dengue Fever, malaria and others. The effect of these arthropod borne diseases are well-known and frequently cause long term and significant impairment if not death to those victims. Millions have been killed from contracting mosquito-born malaria. Efforts to trap mosquitoes, flies, ticks, fleas, chiggers and other insects and arthropods have employed a number of techniques including sticky paper, sprays and chemical attractants. The latter area of investigation has been encouraging because people and animals emit chemicals that are readily detected by these arthropods. Indeed, variations in the combination amount of chemicals emitted from one person to another are a reason why some people are more readily bitten than others.
There area a number of variables that must be considered. For example, a female mosquito may detect a potential bite victim at a distance of 20-40 yards depending on the species and weather conditions. Female mosquitoes are very active between 50° F. and 95° F. in calm or light breeze conditions. The female mosquito is sensitive to a variety of chemicals when beginning a search for a blood meal.
The mosquito is particularly sensitive to carbon dioxide emission for long distance orientation. Of the 340 or more chemicals emitted by humans that researchers have determined attract mosquitoes, carbon dioxide emission is one significant human and animal emission which is a particularly useful attractant for mosquitoes. Carbon dioxide is considered the single most important cue used by mosquitoes for locating a source of blood. Researchers estimate a person giving off 275 ml/min of carbon dioxide result in a concentration of carbon dioxide in the air of between 0.01% and 1.0%, a concentration that is well within the mosquito's ability to detect. J. P. Smith, J. Walsh, and R. Huss recently presented a study of mosquito species and numbers caught in 8 commercial mosquito traps at the American Mosquito Control Association's 2003 annual convention. Seven of the traps produced carbon dioxide by burning propane while one trap did not use carbon dioxide. The non carbon dioxide trap was markedly inferior to the other seven carbon dioxide producing traps.
There are other factors that influence mosquitoes in their search for blood meals. For example, some species of mosquitoes seek areas of increased humidity, moisture, increased temperature, and increased levels of certain compounds usually generated by sweat glands. Additionally, for some species, sound, vision, movement, light, colors and vertical contrast appear to have a role in influencing movement of mosquitoes. The mosquitoes respond to humidity and temperature gradients associated with convection currents and thus factors such as relative humidity play a role in the mosquito's search for a blood meal. Other factors that are believed to affect a mosquito's search for blood meals include the light and time of day and a mosquito's ability to detect movement, color, shapes and patterns. Overall, research suggests that the use of carbon dioxide as a basis for attracting mosquitoes remains an important component in designing effective mosquito traps. Similar considerations apply to attracting ticks, fleas and chiggers. A number of products are commercially available that produce carbon dioxide and use attractants to attract and capture arthropods. However, many of these products use explosive flammable gas such as propane as the main component or dry ice to produce carbon dioxide. Many of these methods are impractical because they cannot be transported safely by aircraft, cannot be used except under well-ventilated areas, and are not readily available or are expensive. Exemplifications of commercially available systems abound. These include, for example, a number that retail from approximately $200 to well over $1500. In addition to costs, these units have other limitations that limit their usefulness. American Biophysics Corp. has sold at least three products in this cost range that use propane to make the carbon dioxide and to generate electrical power needed. It also makes use of a vacuum unit to suck in mosquitoes. Applica Mexico also has a plug-in electrical unit that produces a chemical attractant that requires EPA registration and are useful at all only within range of an electrical power source. Replacement glue trap boards are provided but are very expensive. Flowtron sells an electrical plug-in unit that also requires an EPA registration and uses a vacuum to suck in mosquitoes as does a unit made by Elvert Specialty Products. Coleman provides a unit that burns propane to generate carbon dioxide and further requires EPA registration. Other units sold by Biosensory Inc. have similar limitations and inefficiencies.
Inexpensive, non-electrical, environmentally friendly, controllable methods for generating carbon dioxide for use in insect and/or arthropod traps developed to date have not been generally available. As noted, it is well known that hematophagouos insects and other arthropods are attracted to their hosts by sensing carbon dioxide and this is the basis for numerous previous patents such as Miller, U.S. Pat. No. 5,669,176; Wigdon, et al., U.S. Pat. No. 6,145,243; Paganessi, et al., U.S. Pat. No. 5,943,815; Iwao, et al, U.S. Pat. No. 6,305,122; etc. Previous sources of supplying carbon dioxide gas have included releasing CO2 from tanks, allowing dry ice to gradually sublimate, catalytic conversion of a hydrocarbon fuel in a combustion chamber (U.S. Pat. No. 6,145,243), methanol cells (U.S. Pat. No. 5,669,176), and dropping a calcium carbonate tablet into water (U.S. Pat. No. 6,305,122). Although these methods of supplying carbon dioxide are effective, the associated tanks and/or holding containers tend to be quite large and difficult to handle and/or the rate of CO2 gas release has been difficult to control, sustain and regulate. Some are also associated with devices that require electricity.